DE4410820C2 - Auxiliary air supply device for an internal combustion engine - Google Patents

Description

The invention relates to an auxiliary air supply device for an internal combustion engine according to the preamble of Claim 1.

Fig. 1 shows the general view of a known auxiliary air supply device. The body 1 of an internal combustion engine is in communication with an air flow channel 2 . The air flow channel 2 contains an air filter 3 , an air flow sensor 4 , a throttle body 5 for the gradual release of an air flow, a collecting space 6 for the order of the air flow, an intake manifold 7 , an exhaust manifold 8 , through which the engine 1 led out of the body 1 Air passes, a catalytic device 9 with a catalytic converter for cleaning the exhaust gas and a muffler 10 in the sequence from the inlet side to the outlet side.

An additional air supply line 11 is provided between the air filter 3 and the exhaust manifold 8 in the air flow duct 2 to supply additional air to the catalytic device 9 . In the illustrated exemplary embodiment, an air pump 12 , a through-flow control valve 13 and a shut-off valve 13 a are arranged in the course of the additional air supply line 11 . The air pump 12 and the flow control valve 13 are connected to a control unit 14 , which in turn is connected to a detector device 15 for detecting various conditions.

The mode of operation is described below. Air passing through the air filter 3 and the air flow channel 2 is sucked into the body 1 of the internal combustion engine together with fuel. After combustion, an exhaust gas passes through the exhaust manifold 8 to be diverted to the outside. The exhaust gas in the exhaust manifold 8 contains a large amount of air pollutants such as HC, CO or NO _x , so that the exhaust gas is released into the atmosphere by the catalytic device 9 after a reduction in the air pollution.

At the start of the internal combustion engine, however, the exhaust manifold 8 cannot supply the catalytic device 9 with air that has a temperature for easy reaction with the catalyst and is oxygen-rich, resulting in an insufficient cleaning of the exhaust gas. Therefore, it is neces sary to supply external air through the auxiliary air supply line 11 .

In the illustrated embodiment, the additional air is forcibly delivered by the arranged in the additional air supply line 11 air pump 12 in the laßkrümmer 8 . The control unit 14 decides depending on the data detected by the detector device 15 such as water temperature, revolution, charge or pump pressure. Subsequently, a display from the control unit 14 controls the rotation or the like of the air pump 12 to supply an appropriate amount of air to the upstream part of the catalytic device 9 . Furthermore, in the illustrated embodiment, the display from the control unit 14 can set a deviation of the flow control valve in order to optimize the supply speed of the additional air.

However, in the auxiliary air supply device, external air having a low temperature is led into the catalytic device 9 during the low temperature start time, so that the catalyst cannot react appropriately due to the low temperature. Accordingly, there is a problem that the reaction in the catalytic device 9 can not be promoted effectively.

To overcome this problem, a preheater has been proposed, for example, in Japanese Patent Publication (Kokai) No. 55-29003. As shown in Fig. 1, the preheater 16 is attached to the exhaust manifold 8 and connected to the auxiliary air supply duct 11 .

The preheater transfers preheat from the exhaust gas in the exhaust manifold 8 to heat the auxiliary air in the auxiliary air supply line 11 , thereby reducing a decrease in the temperature of a mixed gas from the exhaust gas supplied upstream from the catalytic device 9 and the auxiliary air to reduce the reaction speed to promote in the catalytic device 9 .

In an alternative embodiment, the additional air is supplied by utilizing the negative pressure in the exhaust manifold 8 without the air pump 12 in the additional air supply line 11 and the control unit 14 being used to control the air pump 12 . Fig. 2 shows a general view of an auxiliary air supply device of this type, which is disclosed, for example, in Japanese Utility Model Publication (Kokoku) No. 3-2663. In Fig. 2, an additional air supply line 11 a and an upstream of this arranged guide valve 11 b shows ge.

The auxiliary air supply device takes advantage of a change in the outlet pressure, which is caused by the intake and Auslaßvor gear in the body 1 of the internal combustion engine. That is, the additional air is supplied by opening the guide valve 11 b, which is provided for the additional air supply line 11 a, in the event of a vacuum in the exhaust manifold 8 , and the Füh approximately valve 11 b is closed to in the event of an excess pressure in Exhaust manifold 8 to prevent a counterflow of the exhaust gas.

The known auxiliary air supply device for a combus- tion machine is formed out as shown above. It is therefore impossible in any case to stably supply the additional air to the catalytic device 9 at a preferred temperature. Accordingly, the catalytic device 9 can not effect sufficient exhaust gas purification and cannot contribute significantly to the prevention of air pollution, which is increasingly desired in view of environmental protection in recent years.

That is, the device shown in Fig. 1 (which is disclosed, for example, in Japanese Patent Publication (Kokai) No. 55-29003) makes use of the preheat from the exhaust manifold 8 and cannot sufficiently raise the temperature of the auxiliary air. if during the start time of the exhaust manifold 8 is not yet hot, which results in insufficient promotion of the reaction in the catalytic device 9 .

Furthermore, in the other apparatus shown in Fig. 2 (which is disclosed, for example, in Japanese Utility Model Publication No. 3-2663), the supply air can be automatically supplied only in the case of a negative pressure in the exhaust manifold 8 . Therefore, a stable supply of sufficient air, which is necessary for the reduction of air pollutants such as HC, CO or NO _x , is impossible, which has a low effect in exhaust gas purification. In addition, it is necessary to supply the additional air during the low-temperature start time, when the catalytic device cannot show its true performance. However, there remains a problem that the efficiency of the catalytic purification is deteriorated because the exhaust gas temperature decreases when excess temperature air is supplied in excess.

From the unpublished DE 43 07 737 A1 a device for supplying fresh air into a Exhaust pipe of an internal combustion engine for cleaning the Exhaust gases known. This has one between one Inlet pipe and an exhaust pipe of the engine arranged Nete air supply device to one in the exhaust pipe supply fresh air to the catalyst, and a heater for heating the air Supply device supplied fresh air, wherein the heated air is fed to the catalyst.

It is the object of the present invention Auxiliary air supply device for an internal combustion engine with an auxiliary air supply path for supplying external ones Air to a catalyst, one in the additional air Exothermic body and a feed path provided the generation of heat by the exothermic body controlling control unit to create that one more improved performance in exhaust gas cleaning supply, especially even during low temperatures door start time.

This object is achieved by the specified in the characterizing part of claim 1  Features. Advantageous further developments of the inventions additional air supply device according to the invention result from the subclaims.

The invention is characterized in that a tem temperature sensor in the additional air supply path for detection the temperature of the exothermic body is provided and that the control unit is generating heat me through the exothermic body according to that of Temperature sensor controls temperature controls.

The exothermic body advantageously contains an elec trical resistance, that of a power source Energy for generating heat is supplied.

A is preferably in the additional air supply path Gas heater provided which is a hollow and cylindrical housing and a positive and a ne negative electrode that is hollow and cylindrical Housing attached and ver with the exothermic body are bound, the exothermic body either by spiral winding one electrical resistance formed and so in the housing is arranged that it is in the axial direction of the housing extending air path, or in a wavy and circularly curved shape such that a leaf-shaped resistor a blu has tabular section, provided and axially is arranged in the housing so that it has an air path forms in this.  

The invention is described in the following in the Figures illustrated embodiments closer explained. It shows:

Fig. 1 shows an embodiment of a known auxiliary air-feeding apparatus,

Fig. 2 shows another embodiment of an auxiliary air-feeding apparatus be known,

Fig. 3 shows a first embodiment of a supplementary air feeding apparatus according to the invention and a suction / off laßsystem an internal combustion engine, wherein the auxiliary air-feeding apparatus is used,

Fig. 4 is a front view of a gas heating apparatus according to the first embodiment,

Fig. 5 is a side sectional view of the gas heating apparatus according to the first embodiment,

Fig. 6 is a front view of a second embodiment of a gas heating device,

Fig. 7 is a side sectional view of the second execution example of the gas heating device,

Fig. 8 is a side sectional view of a third example of the exporting approximately gas heating device,

Fig. 9 is a front view of a fourth Ausführungsbei clearance of a gas heating device,

Fig. 10 is a side sectional view of the fourth execution example of the gas heating device,

Fig. 11 is a side sectional view of a fifth embodiment approximately example of a gas heating device,

Fig. 12 is a side sectional view of a sixth example of a guide from gas heating device,

Fig. 13 shows a the operation of the first execution example of the auxiliary air-feeding apparatus illustrative flow chart

Fig. 14 is a perspective view of a seventh example of a guide from gas heating device,

FIG. 15 is a side sectional view of an eighth From leadership example of a gas heating apparatus,

Fig. 16 is a front view of the eighth embodiment of the gas heating device,

Fig. 17 is a side sectional view of a ninth exporting approximately example of a gas heating device,

Fig. 18 is a front view of the ninth embodiment of the gas heating device,

Fig. 19 is a perspective view of a tenth example of a guide from the gas heating device,

Fig. 20 is a side sectional view of an eleventh exporting approximately example of a gas heating device, and

Fig. 21 is a side sectional view of a twelfth exporting approximately example of a gas heating apparatus.

example 1

There now follows a description of a first embodiment. FIG. 3 shows a gas heating device 17 which is provided for an additional air supply line 11 which serves as an additional air supply path. The parts with the exception of the Gaserwärmungsgerä tes 17 and the associated structures are identical to those in the known device of FIG. 1. These are therefore provided with the same reference numerals and their description is omitted here.

In the auxiliary air supply device according to this embodiment, a vehicle battery 18 serves as a power source and supplies power to the gas heating device 17 for generating heat, and one end of the gas heating device 17 is connected to a control unit 14 . The control unit 14 controls an air pump 12 or a flow control valve 13 depending on the pump pressure, a water temperature, rotation, charging, intake air temperature or the like. The control unit 14 also controls the power supply to the gas heating device 17 in, for example, depending on an exothermic time of the gas heating device 17 or a temperature of an exothermic body of the gas heating device 17 , which is detected by a temperature sensor 19 (which is provided for the gas heating device 17 , such as is described in the sixth exemplary embodiment).

The gas heater 17 generates heat due to the electrical power supplied by the power source. However, it should be noted that the present invention is not limited to this; for example, the heat generation can be brought about by an inherent property in the gas heating device.

As shown in FIGS . 4 and 5, the gas heater 17 includes a housing 20 and electrodes 21 and 22 . The housing 20 has a hollow and cylindrical shape and flange portions 24 are formed at the ends of the housing 20 . The flange areas 24 are coupled by bolts with flange 25 , which are arranged in the course of the additional air supply line 11 . The electrodes 21 and 22 are via spacers 27 by means of screw bolts 38 in holes provided in the housing 20 BEFE Stigt. In the present case, the electrode 21 is a positive electrode and the electrode 22 is a negative electrode.

The housing 20 contains an exothermic body 23 . The exothermic body 23 is formed by spirally winding a sheet, and the sheet includes an electrical resistor 28 (for example, stainless) which serves as a conductor with a predetermined resistance value in such a state that a predetermined surface area is ensured. An area between wrapped sheets is defined as an air path 26 . A connecting strip fen 23 a extends from the central region of the spiral to be connected to the negative electrode 22 , and the other connecting strip 23 b extends from a peripheral edge of the spiral to be connected to the positive electrode 21 . Thus, the exothermic body 23 is supported by the connection strips 23 a and 23 b in the housing and connected in series with the battery 18 . As shown, the exothermic body 23 is formed by spirally winding the sheet electrical resistor 28 , and the area between the wound sheets is defined as the air path 26 . It is possible to ensure an exothermic surface to such an extent that the flowing air can be heated sufficiently.

The method of operation is now described. In the system of FIG. 3, when external air flows through an air filter 3 into an air flow channel 2 , part of the air flows into the auxiliary air supply line 11 and through the air pump 12 and the flow control valve 13 . In particular, during an engine start time, the air pump 12 is driven at high speed to deliver a large amount of air to a catalytic device 9 .

On the other hand, electrical power is appropriately supplied to the exothermic body 23 of the gas heating device 17 for heat generation, for example by opening a relay contact 37 due to the opening of a key switch of a vehicle. When the additional air passes between the electrical resistances of the exothermic body 23 , it comes into contact with them and is heated. In this case, the exothermic body 23 has an axially erstrec kende length, so that the additional air can be heated sufficiently in the time in which it passes through the exothermic body 23 .

The additional air which has passed through the gas heating device 17 leaves the additional air supply line 11 to flow into an exhaust manifold 8 and is mixed with the exhaust gas from the body 1 of the internal combustion engine. Then the mixed air flows into the catalytic device 9 and is released into the outside air after toxic substances such as HC, CO or NO _{x have} been removed from the mixed air by a catalyst.

At this time, the control unit 14 controls the gas heating device 17 depending on a temperature sensor 19 detected value or the like. The operation in this case will be described with reference to FIG. 13.

First, the control unit 14 determines an operating state of the machine 1 when the key switch of the vehicle is opened. If it is determined that heating of the additional air is necessary in this state, the relay contact 37 is opened in order to start the energy supply to the exothermic body 23 . As the temperature of the exothermic body 23 increases with the passage of time, the temperature is detected by the temperature sensor 19 (step A).

On the other hand, it is determined whether or not the temperature reaches the maximum temperature Tmax based on the predetermined maximum temperature Tmax and the predetermined minimum temperature Tmin of the exothermic body 23 (step B). Values of the maximum temperature Tmax and the minimum temperature Tmin can be determined in view of a temperature at which the exhaust gas can react with the catalyst in order to remove the toxic substances easily and effectively. Excessively hot additional air causes damage to the gas heating device and too cold additional air tends to prevent a slight reaction of HC and CO with the catalytic converter. Therefore, the supply air should be supplied at a temperature in such a range that NO _x , HC and CO are completely removed.

In step B, the relay contact 37 is opened when it is determined that the temperature reaches the maximum temperature Tmax or when it is determined whether the temperature reaches the minimum temperature Tmin or not when it is determined that the temperature reaches the maximum temperature Tmax not reached (step C).

If the temperature is determined to reach the minimum temperature Tmin, the voltage applied by the battery 18 to the exothermic body 23 is increased to increase the temperature of the exothermic body 23 . Alternatively, for example, a contact point between the battery 18 and the exothermic body 23 can be moved in a direction in which there is an increase in the resistance value in order to define the electrical resistances forming the exothermic body 23 as variable resistances, where by itself an increased Temperature of the exothermic body 23 results.

The additional air is continuously heated at an appropriate temperature by continuously detecting the temperature of the exothermic body 23 . Next, it is decided whether a time has reached a predetermined leading time or not (step D).

The predetermined time can be determined by a timer arranged in the control unit 14 . The heat generation is no longer required after the passage of time such as the low temperature start time of the machine 1 , in which the additional air with a particularly high temperature is required. Accordingly, such a time is set as a time required for the power supply to be controlled by the exothermic body 23 . If the time in step D does not yet reach the set time, the temperature detection is continued. Otherwise, the relay contact 37 is opened to end the heat generation (step E).

After completion, no electrical power is supplied to the exothermic body 23 before the next opening of the key switch after the machine 1 is stopped. When the temperature of the exothermic body 23 reaches the maximum temperature Tmax in step B, the temperature detection is continued even after the relay contact 37 is opened. Thereafter, when the temperature of the exothermic body 23 has decreased to the minimum temperature Tmin, the relay contact 37 is opened again to supply energy to the exothermic body 23 (step F).

As stated above, with the auxiliary air supply device or the gas heating device, the additional air can be heated as required by the exothermic body 23 provided for the additional air supply line 11 in order to maintain the appropriate temperature. Thus, it is possible to remove the toxic substances such as HC, CO or NO _x with greater effectiveness even at the low temperature start time of the machine 1 and to contribute to a considerable prevention of the air pollution.

In the embodiment, instead of the Luftpum pe 12 and the flow control valve, which are arranged in the additional air supply line 11 , the additional air by excess and negative pressure of the body 1 of the internal combustion engine in the exhaust manifold 8 is performed. Alternatively, the auxiliary air supply line 11 can be branched in its course, and one of the branched lines can be connected to the outlet manifold 8 and the other directly to the catalytic device 9 .

Example 2

With reference to FIGS . 6 and 7, a description is given of a second embodiment of a gas heating device. As shown herein, in the gas heating device 17 according to this embodiment, a housing 20 contains a plurality of exothermic bodies (four of which are shown). Although the exothermic bodies 23 c, 23 d, 23 e and 23 f have the same shape as in embodiment 1, each exothermic body forming electrical resistor 28 can be provided in a thicker shape than that shown in FIGS. 4 and 5 .

Since in embodiment 1 only one exothermic body is provided by 23 , the electrical resistor 28 must have a very thin shape to ensure a pre-determined heat value. In contrast, since four exothermic bodies are used in the embodiment 2, it is possible, in contrast, to provide a predetermined total electrical resistance (of about 100 mΩ), even if the electrical resistors have a relatively thick shape. Therefore, there is the possibility that the device can be designed with an increased degree of freedom and the manufacture of the exothermic body is simplified.

A peripheral edge of the exothermic body 23 c is connected by a connecting strip 23 b to a positive electrode 21 and a cylindrical coupling member 29 (a metal tube) is welded to a central region of the exothermic body 23 c. A hollow region of the coupling member 29 also forms an air path 26 . The other end of the hitch be member 29 is welded to a spiral central region of the adjacent exothermic body 23 d. A spiral peripheral edge of the exothermic body 23 d is connected by a connecting strip fen 23 a to an inner surface of a connec tion ring 30 . The connecting ring 30 is fixed to an inner surface of the housing 20 via an insulating piece 31 .

Furthermore, the exothermic body 23 e is arranged adjacent to the connecting ring 30 and one end of the exothermic body 23 e is fastened via an connecting strip 23 b to an outer circumference of the connecting ring 30 . The exothermic body 23 f is attached adjacent to the exothermic body 23 e and intermediate regions of the exothermic bodies 23 f and 23 e are coupled to one another by the coupling member 29 as in the case of the exothermic bodies 23 c and 23 d. The other end of the exothermic body 23 f is connected to a negative electrode 22 via a connecting strip 23 a. The coupling member 29 and the connecting ring 30 are conductive and the respective exothermic bodies are connected in series with a battery 18 .

Example 3

A description is given of a third exemplary embodiment of the gas heating device with reference to FIG. 8. In embodiment 3, four exothermic bodies are coupled to one another by a coupling member 29 and a connecting ring 30 in the axial direction of a housing 20, as in embodiment 2. However, the electrical Wi resistors 28 and air paths 26 of opposite exothermic bodies, that is, each pair of exothermic bodies 23 c and 23 d, exothermic bodies 23 d and 23 e and exothermic bodies 23 e and 23 f are arranged so that they are offset from each other in the radial direction. In the arrangement according to this exemplary embodiment, in the event that the electrical resistance 28 of an exothermic body extends in the axial direction of the housing 20 , the air path of the adjacent exothermic body is arranged on the extension. Furthermore, in this exemplary embodiment, the arrangement is realized by moving a rotational position around a spiral central region of the opposite, to the coupling member 29 welded exothermic body by 180 °.

The respective exothermic bodies are arranged as described above, so that, for example, air passing through the exothermic body partially flows around a peripheral edge of the electrical resistor 28 in order to pass through an intermediate region of the air path of the next exothermic body. Conversely, air flows through the intermediate region of the air path of the exothermic body around the peripheral edge of the electrical resistance of the exothermic body. Therefore, it is possible to heat the air passing through the gas heating device 17 evenly. This results from the fact that the air tends to pass linearly through the gas heating device 17 . On the other hand, from the air passing through the exothermic body, the air flowing past in the vicinity of the electrical resistance can be heated more easily than the air passing through the intermediate region of the air path. Accordingly, it is possible to uniformly heat the air as a whole by mutually displacing the adjacent exothermic bodies.

Example 4

. 9 and 10 will now be given with reference to FIG functionality descriptions of a fourth embodiment of the gas heating device. In this embodiment, between areas of two or more respectively coupled exothermic bodies are mutually coupled by a rod 32 and both ends of the rod 32 are supported by plate-shaped holders 33 , in which window holes 34 are provided. The rod 32 is made of metal to ensure sufficient strength most. An insulating coating is applied to the periphery of the rod 32 and the insulating coating is in contact with the intermediate areas of the respective exothermic bodies. The holder 33 are adapted to the inner surface at both ends of a hous ses. With the exception of the features described above, the design is identical to that according to exemplary embodiment 2.

In the gas heater, two or more exothermic bodies are supported by the rod 32 to mutually couple the central regions of the exothermic bodies, and the rod is supported by the holders 33 at the ends of the housing 20 . As a result, it is possible to facilitate the assembly of the exothermic bodies and to stabilize the assembled state, which results in an increased resistance to vibrations.

Example 5

A description of a fifth exemplary embodiment of the gas heating device is given with reference to FIG. 11. In this embodiment, a convex cone member 36 hen in the central region of a holder 33 on the air inlet side of a gas heating device, which is described in embodiment 4. In the gas heater, the inflowing air can be led to a peripheral edge of an exothermic body along a peripheral surface of the cone member 36 so that the air flows uniformly through the entire gas heater 17 , thereby enabling heating with great effect.

That is, the air passing through in an intermediate region of an air line typically has a higher flow velocity than that in the peripheral region of the line. Thus, the air has a tendency to be concentrated in the intermediate region of the exothermic body after it has entered the gas heating device. In this case, however, the cone member 36 forcibly directs the air flowing in the intermediate area to the outside. This makes it possible to achieve a uniform flow velocity distribution and to guide a large proportion of the air through the peripheral region of the exothermic body, which has a particularly large exothermic area.

In the illustrated embodiment, the cone member 36 is fastened to the central region of the holder 33 . However, it should be noted that the same effect can be achieved by arranging the cone member 36 by suitable means in the central region of an opening on the air inlet side of the gas heating device without the holder 33 .

Example 6

A description will be given of a sixth embodiment of the gas heating apparatus with reference to FIG . In this embodiment, a temperature sensor 19 is attached to an exothermic body. The training with the exception of the attached temperature sensor 19 is identical to that according to example 4. With the temperature sensor 19 , a control unit can follow a control with respect to an appropriate temperature in the auxiliary air supply device depending on a temperature detection of the exothermic body, such as is described in embodiment 1 .

Example 7

A description of a seventh exemplary embodiment of the gas heating device is given with reference to FIG. 14. Detailed structures such as a power source for the gas heating device or a structure and operation of an auxiliary air supply device in which the gas heating device is used are identical to those in the embodiment 1. Therefore, the same reference numerals may be used and the illustration and description thereof waived here.

The gas heating device according to embodiment 7 contains a housing 120 , electrodes 121 and 122 and an exothermic body 123 . The housing 120 has a hollow and cylindrical shape and is arranged in the course of an additional air supply line 11 . A flange coupling, a pipe insertion method or the like is used as a typical connection method, but it is not shown in FIG. 14. The electrodes 121 and 122 are positive and negative electrodes corresponding to the electrodes 21 and 22 in the embodiment 1, and they are connected to the exothermic body 123 . The housing 120 contains the exothermic body 123 and the exothermic body 123 contains an electrical resistor (for example, a stainless plate), which has a substantially bluebottle shape and has a predetermined resistance value, as shown in FIG. 14. Furthermore, spaces 124 a and 124 b are formed on the inside and the outside of the petal-shaped exothermic body 123 and are determined as air paths.

In the gas heating device, it is possible to improve the cleaning ability by increasing the temperature of the supply air as in the operation according to the embodiment 1. In addition, there is the possibility of easily ensuring an exothermic area in order to heat the flowing air sufficiently, since air paths are present both on the inside and on the outside of the substantially petal-shaped exothermic body 123 .

Example 8

Referring to FIGS. 15 and 16, a description will be made of an eighth embodiment of the gasifier wärmungsgerätes. In this embodiment 8, a housing 120 contains an exothermic body 123 , and both ends of the exothermic body 123 are supported by and are arranged between heat-resistant insulators 125 with essentially honeycomb through holes. From the formation of the exothermic body 123 is identical to that of embodiment 7.

In the gas heating device according to embodiment 8, the exothermic body 123 can be held securely by the warmer resistant insulators 125 , so that the exothermic body 123 , which is essentially petal-shaped electrical resistance, can have a thinner design than that in the exemplary embodiment 7 according to FIG. 14 while maintaining vibration resistance or the like. This makes it possible to increase the surface area and to provide the same resistance value by forming a thinner shape for the exothermic body 123 and, for example, extending in the axial direction. As a result, by increasing the contact area with the air, the heating effect can be increased, and the vibration resistance ability or the like can also be improved by deforming the electrical resistance or by reducing the vibration or the like.

Example 9

. 17 and 18, a description will be given of a ninth embodiment of the gas heating apparatus with reference to FIG. In this embodiment, a plurality of exothermic bodies 123 a, 123 b and 123 c each have a different width (ie an axial length) and are connected to one another in series, and the respective exothermic bodies are formed at their end faces by heat-resistant insulators 125 a, 125 b, 125 c and 125 d supported.

Fig. 18 shows the view in the axial direction of the gas heating device according to this exemplary embodiment. An insert groove 126 is provided in a side surface of each heat-resistant insulator at a position where the exothermic body is located. Both ends of each exothermic body in each layer are inserted into and held by the insert grooves 126 provided in the heat-resistant insulators.

Although the configurations of the respective exothermic bodies in the gas heating device are identical to those according to embodiment 7, an electrical resistance forming the exothermic body can be thicker than in embodiment 7. That is, the gas heating device in FIG. 14 contains an exothermic body, so that the electrical resistance must have a very thin shape to ensure a predetermined heat value. In contrast, who uses the three exothermic bodies in embodiment 9, so that each exothermic body can have a relatively thick shape, even if each exothermic body has the same total surface area, and a predetermined electrical resistance (of approximately 100 mΩ) can be provided in total will.

Since in the embodiment 9, the exothermic body each having a different width, each resistance value of each exothermic body can be expressed even with the same thickness as the exo thermenregion body 123 a 'of the exothermic body 123 b' of the exothermic body 123 c. Accordingly, even with the same power consumption (ie, the same total resistance value), each heat value of each exothermic body can be expressed as the exothermic body 123 a <the exothermic body 123 b <the exothermic body 123 c. The exothermic body 123 c thus reaches the highest temperature, so that the additional air can be heated effectively.

In the event that the exothermic bodies with the same resistance are arranged in series with respect to a flow direction of the air, the gas temperature on the upstream side (ie on the inlet side) of the gas heating device is typically low. Thus, the air is heated successively as it passes through the exothermic body, resulting in an elevated temperature. At this time, the difference between the inlet gas temperature of each exothermic body and the temperature of the exothermic body itself decreases more and more as the air flows to the subsequent stages. That is, since the temperature difference decreases more and more, the heat conduction from the exothermic body to the gas decreases more and the effectiveness of the heat transfer is further reduced, so that the exothermic body cannot be used effectively on the downstream side. However, since in the gas heating device according to this embodiment, the heat generation of the exothermic body on the downstream side is increased, it is possible to increase the effectiveness of the heat transfer, especially a response characteristic (ie, a temperature rise speed). Although in this embodiment the size of the resistance value of each exothermic body is defined as the exothermic body 123 a <the exothermic body 123 b <the exothermic body per 123 c, it should be noted that the present invention is not limited to this order.

Furthermore, each exo is in the gas heating device thermal body partially into an essentially wa ben-shaped heat-resistant insulator and  attached by this. Accordingly, the exothermic Body resist vibration and shock, even if it is thinner to its surface to increase. As a result, the heating effect may be white ter be increased.

Example 10

A description is given of a tenth embodiment of the gas heating apparatus based on Fig. 19. In this exemplary embodiment 10 , pores 127 pass through the entire surface of an exothermic body 123 . The other training of the gas heating device is identical to that of embodiment 7 and the illustration and description thereof is omitted. In this gas heater, a gas passes the exothermic body 123 through the pores 127 in a substantially turbulent state. As a result, the effectiveness of the heat transfer is improved in order to enable the additional air to be heated more effectively.

Example 11

Referring to FIG. 20, a descrip now be bung of an eleventh embodiment of the gas heating device. In this exemplary embodiment 11, the gas heating device contains exothermic bodies 123 a, 123 b, 123 c and 123 d, the two ends of which are supported by heat-resistant insulators 125 a, 125 b, 125 c and 125 d and which are electrically connected in series. The heat-resistant insulator 125 a is arranged on the single end side of the gas heating device to come into contact with a projecting part of a housing 120 , and for example a conical spring-like elastic body 128 is between the heat-resistant insulator 125 a and the projecting part of the housing 120 ordered on.

Since in the gas heater, each exothermic body is elastically secured in the housing 120 in the axial direction, it is possible to smoothly suppress axial vibrations and to absorb axial thermal expansion of each exothermic body. Therefore, it is possible to protect the exothermic body from vibrations or thermal stress, so that its life or the like is increased. The elastic body 128 is preferably fixed on the gas inlet side, that is, on the side with the lower gas temperature.

Example 12

A description will now be given of FIG. 21 of a twelfth embodiment of the gas heating device. In this embodiment, example 12, an inorganic fibrous heat-resistant insulator 129 is disposed between the outer periphery of each exothermic body and heat-resistant insulator and the inner periphery of a case 120 . In this case, the heat-resistant insulator 129 for the inner wall of the housing 120 is provided in a substantially cylindrical shape.

In this gas heater, the heat-resistant insulator 129 is interposed to prevent heat transfer from the exothermic body inside the case 120 , so that the heat transfer to the case 120 is reduced. As a result, it is possible to increase the effectiveness of heat transfer to the make-up air, so that more effective heating is enabled.

Claims (14)

1. Auxiliary air supply device for an internal combustion engine with an auxiliary air supply path for supplying external air to a catalyst, an exothermic body provided in the auxiliary air supply path and a control unit controlling the generation of heat by the exothermic body, characterized in that that a temperature sensor ( 19 ) in the additional air supply path ( 11 ) for detecting the temperature of the exothermic body ( 23 ) is provided, and that the control unit ( 14 ) the generation of heat by the exothermic body ( 23 ) accordingly that of the temperature sensor ( 19 ) detected temperature controls. 2. Feeder according to claim 1, characterized in that the exothermic body ( 23 ) contains an electrical resistor ( 28 ), which is supplied with energy from a power source ( 18 ) for generating heat. 3. Feeder according to claim 1, characterized in that in the additional air supply path ( 11 ) a gas heating device ( 17 ) is seen before, which comprises:
a hollow and cylindrical housing ( 20 ) and a positive and a negative electrode ( 21 , 22 ) which are attached to the hollow and cylindrical housing ( 20 ) and connected to the exothermic body ( 23 ), and that the exothermic body ( 23 ) formed by spiral-shaped winding of an electrical resistor ( 28 ) and is arranged in the housing ( 20 ) so that it forms an air path extending in the axial direction of the housing ( 20 ). 4. Feed device according to claim 1, characterized in that in the additional air supply path ( 11 ) a gas heating device ( 17 ) is seen before, which comprises:
a hollow and cylindrical housing ( 120 ) and a positive and negative electrode ( 121 , 122 ) attached to the hollow and cylindrical housing ( 120 ) and connected to the exothermic body ( 123 ), and
that the exothermic body ( 123 ) in a corrugated and annularly curved shape such that a leaf-shaped resistor has a flower-leaf-shaped section, is provided and axi al in the housing ( 120 ) is arranged so that it forms an air path therein. 5. Feeder according to claim 3 or 4, characterized in that the exothermic body ( 23 , 123 ) is leaf-shaped. 6. Feeding device according to claim 3 or 4, characterized in that the exothermic body has a plurality of exothermic parts ( 23 c to 23 f), which are arranged at mutual intervals in series axially in the housing ( 20 ), and that the exothermic parts ( 23 c to 23 f) are mutually coupled by a coupling member ( 29 ). 7. Feeding device according to claim 5, characterized in that the exothermic body has mutually opposite exothermic parts ( 23 c to 23 f) which are arranged so that their air paths are not aligned with each other. 8. Feeding device according to claim 6, characterized in that the coupling member ( 29 ) contains a rod ( 32 ) for coupling against lateral central regions of the exothermic parts ( 23 c to 23 f), both ends of the rod ( 32 ) by one on the housing ( 20 ) fastened holder ( 33 ) is supported, which is provided with a window hole ( 34 ) for the passage of air. 9. Feeder according to claim 3 or 4, characterized in that a convex cone member ( 36 ) is arranged in the central region of an opening on the air inlet side in the housing ( 20 ) to face the opening. 10. Feeder according to claim 3 or 4, characterized in that both ends of the exothermic body ( 123 ) by a heat-resistant insulator ( 125 ) with many through holes for attachment to the housing ( 120 ) are supported. 11. Feeding device according to claim 3 or 4, characterized in that the exothermic body has several exothermic parts ( 123 a to 123 c), which are arranged in series axially in the housing ( 120 ), and the exothermic parts ( 123 a to 123 c) have different resistance values. 12. Feeder according to claim 3 or 4, characterized in that the exothermic body ( 123 ) with a large number of pores ( 127 ) is hen, through which a gas freely enters and exits. 13. Feeder according to claim 3 or 4, characterized in that an elastic body by ( 128 ) between a heat-resistant Isola gate ( 125 a), which is the most heat-resistant Isola gates ( 125 a to 125 d) upstream, and that Housing ( 120 ) is arranged. 14. Feeder according to claim 3 or 4, characterized in that an elastic heat-resistant insulator ( 129 ) between the outer circumference of the exothermic body ( 123 ) and the heat-resistant insulator ( 125 ) and the inner circumference of the housing ( 120 ) is arranged .